1. Field of the Invention (Technical Field)
The present invention relates to methods and devices for cooling turbomachinery components. More particularly, the present invention utilizes one or more venturi devices upstream of the compressor for delivering cooling air to turbomachinery components, such as for cooling airfoil bearings of turbomachinery or motor windings of electric assist turbomachinery.
2. Description of Related Art
Turbomachinery, such as internal combustion engine turbochargers and similar devices, is employed to compress gas using a centrifugal pumping action. Typically turbochargers are powered by the exhaust gas from gasoline or diesel engines, optionally with electric assist motors. The exhaust of these engines is typically routed to the turbine component of the turbocharger directly from the exhaust manifold of the internal combustion engine.
The heating associated with compressing a gas, typically intake air, together with the turbine being powered by hot exhaust gases, results in high operating temperatures for turbochargers. The high temperatures that are continuously endured by the various components of turbomachinery results in decreased operating life of the turbomachinery.
Certain turbochargers are “oil-less” in that they do not employ oiled or greased bearing components. These turbochargers typically employ airfoil bearings adjacent to turbine rotors, the airfoil bearings being gas lubricated. Airfoil bearings require a supply of gas, typically air, to maintain bearing temperature within an optimal range, particularly the desired operational temperature of the foils or elastic materials of the airfoil bearings. Electric assist turbochargers employ an electric motor, including a motor stator, to assist in providing rotational energy for the compressor. The motor stator and associated components is preferably provided with air for cooling. Both airfoil bearings and the motor stator in electric assist turbochargers components are especially at risk of failure at high operating temperatures. The conventional method of providing cooling to these components is to cause some portion of the high-pressure air downstream of the compressor to be made to pass by these components. However, this high-pressure air is at a high temperature due to the heat produced as a result of having just been compressed. Thus a relatively large volume of air must be used to provide sufficient cooling. The use of large volumes of air for cooling purposes reduces the volume of compressed air that is available for use by the engine. This reduction in the volume of air supplied to the engine results in reduced engine performance. There is thus a present need to provide devices and methods cool the components of turbomachinery, particularly airfoil bearings in turbines and motor stators in electric assist turbines, while maintaining the maximum possible volumetric flow of compressed air to the engine.